1. Field of the Invention
This invention relates to a wire-and-pulley drive link mechanism and a control system for driving the same, more particularly to a wire-and-pulley drive link mechanism for a robot hand or the like and a control system for driving the link mechanism.
2. Description of the Related Art
A wire-and-pulley drive link mechanism for a robot hand or the like, specifically a wire-and-pulley drive articulated mechanism is taught, for example, by Japanese Patent Laid-Open Application No. Hei 6(1994)-8,178. This system is a multifinger hand similar to the human hand. It has four frames successively connected to a base through four joints.
As disclosed in the reference, a number of motors corresponding to the number of joints are mounted on the base. The output shaft of each motor is fitted with a drive pulley. Each frame is driven by pulling it with a wire wound about a driven pulley fixed thereon so as to give the frame a degree of freedom, e.g., rotational. One end of a cantilever is fixed to the base to impart tension to the wire. A strain gage is pulled by the cantilever and the tensile force in the wire is measured by detecting the amount of bending thereof. The detected tensile force is fed to the motor controller for feedback control so as to prevent overloading of the hand.
With this prior-art arrangement, however, the detection means for detecting the tensile force acting on the wire is constituted as being separate from the wire. This increases the weight of the hand and makes the configuration complex. Moreover, to increase the detection accuracy in this system, it is generally necessary to reduce the strength of the portion which is subject to force for detection. This is problematic, however, since it frequently results in insufficient strength of the overall system.